The present invention generally relates to a video tape recorder of a type utilizing a cassette tape and, more particularly, to a tape loading apparatus in the video tape recorder for drawing a portion of magnetic video tape out of the tape cassette for urging the tape around a tape guide cylinder.
Currently commercially available video tape recorders of the helical scan type, with the exception of those for professional use, are designed so that when a tape cassette having a length of magnetic video tape reeled therein is inserted in a cassette holder of the video tape recorder and is then brought to a set position from above, a portion of the video tape can be drawn out from a "mouth" of the tape cassette and can be subsequently urging the tape around a tape guide cylinder generally in a configuration similar to the shape of a figure ".OMEGA.". Information recording or reproduction with respect to the video tape is performed by one or more rotary heads after that portion of the video tape has been urged around the tape guide cylinder. In these video tape recorders, a tape loading apparatus is utilized which comprises a pair of spaced tape drawing means each including a tape drawing member and a tape guide member. In recorders in which the tape guide cylinder is mounted on a chassis with its longitudinal axis inclined at a relatively great angle with respect to the chassis and the pair of tape drawing means are supported for movement above the chassis in the same plane (two-dimensional plane), the tape drawing member and the tape guide member of each tape drawing means can be arranged in a side-by-side relationship with each other in a direction perpendicular to the direction in which that portion of the video tape is drawn, that is, in a direction lengthwise of that portion of the video tape exposed to the outside from the mouth of the tape cassette, then held in the set position, and therefore, there is a possibility that, as the tape cassette is brought to the set position, that portion of the video tape may be trapped between the tape drawing member and the tape guide member of one or both of the tape drawing means. Once that portion of the video tape is trapped in between the tape drawing member and the tape guide member, and when the tape drawing means are subsequently moved for urging the tape around the tape guide cylinder, that portion of the video tape and, hence, the whole length of video tape in the tape cassette will be detrimentally impaired.
However, with the advent of a small-sized and light weight video tape recorder of the helical scan type, not only is an arrangement provided in which the tape guide cylinder has a relatively reduced outer diameter and the tape guide cylinder is mounted on the chassis with its longitudinal axis inclined at a relatively small angle to the chassis, but also, in order for that portion of the video tape to be wrapped 270.degree. around the tape guide cylinder, one of the tape drawing means which, when having been moved to a loaded position at which that portion of the video tape has been turned around the tape guide cylinder in preparation for information recording or reproduction, occupies a leading position with respect to the direction of the forward run of the video tape is supported at a level higher than the other of the tape drawing means which at that time occupies a trailing position with respect to the direction of the forward run of the same video tape. This type of video tape recorder may require that the tape guide members be positioned rearwardly of the associated tape drawing members with respect to the tape drawing direction in which that portion of the video tape is drawn out from the mouth of the tape cassette. FIG. 1 of the accompanying drawing illustrates, in perspective, a tape loading apparatus contemplated for use in the above discussed type of video tape recorder.
In FIG. 1, the tape cassette 1 having a length of magnetic video tape 4 is partially shown. As is well known, the tape cassette 1 is rectangular and has one of a pair of opposite sides formed as a "mouth" of the tape cassette 1, the mouth being selectively closed and opened by an elongated, hingedly supported flap 3. At the mouth of the tape cassette, the tape cassette 1 has a pair of spaced recesses 2a and 2b for accommodating the tape drawing means 6 and 12 entering therein from below when the tape cassette 1 inserted into the cassette holder (not shown), and is held at the set position. The flap 3 normally closing the mouth of the tape cassette 1 opens automatically, as the latter approaches the set position as is well known to those skilled in the art, to permit that portion of the video tape 4 confronting the mouth of the tape cassette to be exposed to the outside of the tape cassette 1. As is shown so far, the tape cassette 1 is of a design conforming to the well-known VHS (Video Home System) standards.
The tape guide cylinder, generally identified by 5, is mounted on the chassis with its longitudinal axis inclined at a relatively small angle to the chassis. The tape guide cylinder 5 comprises a rotary drum 5a carrying a plurality of, for example, four, video recording and/or reproducing heads 5c, and a stationary drum 5b having its outer peripheral surface formed with a tape guide groove which extends generally helically about the tape guide cylinder as a whole. Although not shown because they are well known expedients, a rotary transformer and a drive motor for driving the rotary drum 5a in one direction also comprises the rotary drum 5.
The tape drawing means 6 includes the tape drawing member 8 and the tape guide member 9 both mounted on a movable base 7 adapted to slide between an unloaded position, as shown, and a loaded position, defined by a stopper 10, along a grooved guide member 11 while guided by the guide groove in the grooved guide member 11. The grooved guide member 11 is slanted upwardly from the unloaded position, and hence, the tape drawing means 6 as a whole, moves upwardly when moved towards the loaded position so that, when the trailing and leading tape drawing means 6 and 12 have arrived at the unloaded position, the tape drawing means 6 is at a relatively higher position than is the tape drawing means 12, above the chassis. In this tape drawing means 6, the tape guide member 9 is positioned rearwardly of the tape drawing member 8 with respect to the tape drawing direction, i.e., the direction in which that portion of the video tape 4 is drawn out from the tape cassette 1 when held at the set position. And moreover, in view of the shape and size of the recess 2a in the tape cassette 1, the tape guide member 9 mounted on the movable base 7 is inclined towards a free end of the adjacent tape drawing member 8.
The tape drawing means generally identified by 12 is similar in construction to the tape drawing means 6 and includes the tape drawing member 13 and the tape guide member 14 both mounted on a moveable base (not shown) adapted to be moved between an unloading position, as shown, and a loading position, defined by a stopper 15, along a grooved guide member 16 while guided by the guide groove in the grooved guide member 16. This tape drawing means, when at the loading position, is held at a relative elevation equal to or substantially equal to that occupied by the same when held at the unloading position, but is held at a relatively lower position than the position occupied by the tape drawing means 6 when the latter is at the loading position. Accordingly, although the tape guide member 14 is positioned rearwardly of the tape drawing member 13 with respect to the tape drawing direction, it is not inclined as is the tape guide member 9, but is mounted on the movable base so as to extend parallel to the adjacent tape drawing member 13.
It is to be noted that, since the recess 2b in the tape cassette 1 conforming to the VHS standards has a depth greater than the recess 2a in the same tape cassette 1, the tape guide member 14 may have a diameter greater than that of the tape guide member and may be juxtaposed rearwardly and in the vicinity of the adjacent tape drawing member 13.
In the contemplated tape loading apparatus shown in and described with reference to FIG. 1, however, it has been found that, when the tape cassette 1 is brought to the set position by being lowered from above in a direction shown by the arrow A to reach the set position, that portion of the video tape 4 exposed through the mouth of the tape cassette 1 may often be trapped between the tape drawing member and the tape guide member of one or both of the tape drawing means 6 and 12, particularly between those of the tape drawing means 6 as shown by the phantom line in FIG. 1. Once this happens, and when the video tape recorder is subsequently set in operation with both of the tape drawing means 6 and 12 driven towards the respective loading positions, that portion of the video tape 4, and, hence, the length of video tape 4 as a whole, will be detrimentally impaired to such an extent that video and audio information contained in that portion of the video tape 4 will no longer be reproduced, or to such an extent that the operator or user of the video tape recorder who wishes to make a recording of, for example, televised video and audio information will have to discard the cassette tape because of the presence of that detrimentally impaired portion of the video tape 4.
The above described problem appears to result from the fact that, as the tape cassette 1 inserted into the cassette holder (not shown) is shifted in the direction of arrow A, air present beneath the tape cassette 1 is compressed to produce air pressure acting in a direction, shown by the arrow B, forcing a portion of the video tape 4 confronting the recess 2a in the tape cassette 1 to be bent in a direction inwardly of the recess 2a. This is, however, not the only cause of the problem, and it appears that a similar phenomenon may occur as a result of the particular arrangement and coordination of the component parts including a cabinet, and/or when the cassette holder is manually quickly pressed down to move the tape cassette 1 in the direction of arrow A. A still further cause of the problem includes the loosening of the length of video tape within the tape cassette 1.
With respect to the leading tape drawing means 12, the above discussed problem may occur less likely therewith because the recess 2b in the tape cassette 1, which is operatively associated with the leading tape drawing means 12, has a relatively great depth, as compared with that of the recess 2a, i.e. one that is sufficient to allow the tape drawing and guide members 13 and 14 to be positioned set-back from the tape drawing means 6 in a direction away from the tape guide cylinder 5.